Print line registration indicator for type belt

ABSTRACT

A type belt having spaced apart type characters thereon, also has a plurality of timing marks, one for keeping track of the different character positions. A transducer is positioned to sense the timing marks as they move in a horizontal direction for operating print controls in timed relation with the positions of the type characters as they move along the print line and also detect differences in amplitude of the transducer output signals caused by vertical movement of the type belt. The output is used to operate indicating means which tells which position will print next, and which can also be used to enable the operator to detect misregistration of the type belt, so that the operator may correct it.

United States Patent 1191 Bonafino et al.

[11] 3,828,669 Aug. 13, 1974 PRINT LINE REGISTRATION INDICATOR FOR TYPE BELT [73] Assignee: International Business Machines Corporation, Armonk, NY.

[22] Filed: Sept. 8, 1972 [21] Appl. No.: 287,323

3,463,081 8/1969 Levine 101/111 X 1 3,497,121 2/1970 Gold et al. 226/45 3,567,091 3/1971 Woolard 226/45 3,575,107 4/1971 McDowell.... 101/111 X 3,629,861 12/1971 Marsh, .lr 101/111 X 3,719,139 3/1973 Niccolai 197/53 X 3,724,371 4/1973 Picard 101/111 X Primary ExaminerJ. Reed Fisher Assistant Examiner-Paul .1. Hirsch Attorney, Agent, or Firm-Francis V. Giolma ABSTRACT U656 Cl. A type having spaced apart type characters [5 Int. thereon also has a plurality of timing marks one for Field 01 Search keeping track of the different character positions. A 101/93, 111, 2 111 226/45 transducer is positioned to sense the timing marks as they move in a horizontal direction for operating print 1 References Cited controls in timed relation with the positions of the UNITED STATES PATENTS type characters as they move along the print line and 2,802,666 8/1957 Crosfield 101/181 x also detect differences in amplitude of the transducer 3,041,965 7 1962 Sasaki 101/111 P Signals Caused y vertical movement of the 3,068,787 12/1962 Dall Oglio et al. 101/181 type belt. The output is used to operate indicating 3,152,542 10/ 1964 Chambon 101/181 means which tells which position will print next, and 3,225,988 12/1965 Drenning 226/45 can also be used to enable the perator to de- 3,248,524 4/1966 521111161 235/611 1 E t t i i t ti f th t b lt so th t th p 3,303,775 2 1967 G1annuzz1 101 111 tor may correct it 3,323,699 6/1967 Bricker, Jr. 226/45 3,366,876 l/1968 Kurth et a1 226/45 X 1 Claim, 5 Drawing Figures /V\ F7 16 \H 1 L! 11J |FL 14 1 1:5 1 i 7 1 24% 111u 11uk11 1111|11|111|11|11111111g111 3.a28,ss9

PATENTE AUG] 31974 sum 1 0r 2 V l lllllllllllllllllllll FIG. 3

SIGNAL FROM MISALIGNED BELT C M I FIG. 4-

(a) 1V V v OPTIMUM (MAXIMUM) SIGNAL WARN l WILMM, W

PATENTED RUE 1 31974 sum 2 0r 2 saw 258 EEEOQ 2% 1 PRINT LINE REGISTRATION INDICATOR FOR TYPE BELT DESCRIPTION OF THE PRIOR ART Position control of a moving strip of steel by means of a photocell sensing the edge of the strip and a roll whose axis of rotation is pivoted in response to the output of the photocell is disclosed in US. Pat. No. 3,313,461.

SUMMARY or THE INVENTION The invention relates generally to printers and it has reference in particular to printers having type characters on an endless belt movable between spaced apart pulleys along a print line.

More specifically, the invention relates to using the timing marks on an endless type belt for detecting movement of the belt out of its normal line of travel.

Another object of the invention is to provide for using a single transducer with an endless type belt having a plurality of timing marks for keeping count of the next print position and for also determining any departure from the optimum type belt registration position.

Yet another object of the invention is to provide for using a counter and indicating means for both selectively indicating which print position is the next to be printed and what the amount of misregistration of the print belt may be.

It is also an object of the invention to provide for using timing marks on a continuous type belt for operating a counter to both indicate which position is next to print and indicate the relative vertical position of the type belt relative to a normal print line position.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention as illustrated in the accompanying drawing.

DESCRIPTION OF THE DRAWING In the drawing: I

FIG. 1 is a partial schematic view showing a type belt and transducer in accordance with the teachings of the invention;

FIG. 2 is an enlarged partial schematic showing of the type belt and transducer with the belt out of registration in a down or low operating position;

FIG. 3 is an enlarged partial schematic showing of the type belt and transducer with the belt out of registration in an up or high position;

FIG. 4 shows curves illustrating the relative outputs of the transducer for optimum and off-registration conditions and FIG. 5 is a schematic diagram of a circuit used with the transducer and counter for indicating which position is next to print and what the vertical alignment position of the type beltis.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIG. 1, the reference numeral 10 denotes an endless type beltwhich may comprise a relatively thin band of stainless steel having a plurality of spaced Fingers 12 along one edge provided with'raised Print Characters 14, and positioned torun between spaced apart Pulleys l6 and 18 for presenting a relatively straight line of travel along a print line. The Axis 13 of the Pulley 18 is tiltable to the right as represented by the dot-dash line 13' and to the left as represented by the dot-dash line 13" for lowering or raising the Belt 10 on thepulleys. The Belt 10 is also provided with a plurality of Timing Marks 20, which are scanned by a transducer such as the Magnetic Transducer 24, which is positioned adjacent the Pulley 16, preferably in vertical alignment with the TimingMarks 20. The Timing Marks 20 and the Type Characters 14 are preferably raised and may be formed through an etching process which etchesaway the remainder of the belt surface leaving raised Print Characters 14 and Timing Marks 20.

Since the Type Belt 10 may be-readily changed for providing different type fonts, it happens that belts of slightly different widths may be used. This permits the type belt to wander in a vertical direction. For example, as shown in FIG. 2, the Type Belt 10 may have a down creep so that the type characters and timing marks are positioned below their normal position by an amount 0. Since this causes misregistration of the type characters, it is desirable to correct this condition, which may be done by tilting the Axis 13 of the Pulley 18 to the left position as shown by the dot-dash line 13". This causes the type belt to rise and correct the down creep. An up creep condition is shown in FIG. 3 where the Belt 101 is above its normal position by an amount b, again caus-. ing misregistration of the type characters. This condition may be corrected by tilting the axis of the Pulley 18 to the right as shown by the dot-dash line 13'. By having the Transducer 24 normally aligned with the Type Marks 20 in the vertical direction, for the desired operating position of the Belt 10', movement of the belt up or down from this normal position causes misregistration of the Timing Marks 20 with the Transducer 24, and causes a change in the output signal from the transducer as shown by the curves 0 and d in FIG. 4, which represent the optimum and off-registration outputs, respectively. This variation in output signal may be utilized to indicate the belt position to an operator so that he may change the tilt of the Pulley l8 and correct the position of the Type Belt 10'.

Referring to FIG. 5, a Counter 30, which may be of the binary coded decimal type, is connected through suitable decode means, such as a group select Decode Circuit 32, and individual Decode Circuits 34, and 36 in conjunction with an Inverter 38 for controlling a plurality of indicating devices such as the lightemitting Diodes 41 and 42, which are representative of a plurality of diodesnumbering 132, each representing a print position on the print line of a printer. The Counter 30 is normally advanced by means of Print Compare or Space signals from Printer Control Circuits 43 through NOR 44, NAND 4 and NOR 48. The Counter 30 is reset by a signal applied over Conductor 50 and is decremented by means of a Backspace signal applied over Conductor 52.

In order to use the Counter 30 for also controlling the light-emitting Diodes 41-42 to indicate the relative verticalposition of the Type Belt 10, NAND 54 is connected to NOR 48 for operating the Counter 30 in response to clock signals applied over Conductor 56. A Ramp circuit is provided, comprising a Capacitor C arranged to be charged through a Diode D1, and provided with a discharge circuit including a resistor R,

which is adjustable, for controlling the connection of the clock pulses to the Counter30. Theoutput of the Transducer 24 in response to the passage of Timing Marks thereby is applied to an Amplifier 62 and then to a Rectifier andFilter Circuit 64, which is connected to the base of a transistor Tl, whose emitter is connected to the ramp Capacitor C. A diode D2 and an Inverter 66v are connected between the anode of the diode D1 and the Rectifier-and Filter Circuit 64. A transistor T2 controlled by Transistor T1 is connected through an Inverter 68 to the NAND 54 to control the gating of pulses from :1 Clock 56 to the Counter 30. A Switch 70 is provided for connecting Conductor 74 to ground when it isdesired to check the registration of the Type Belt 10. A conductor 74 is connected to a plus source of electrical energy through a Resistor 72. Inverter 76 connects the Conductor 74 to a Conductor 78 connected to the NAND 54 and to a NAND 80 in With the CE switch 70 in the normal position the Counter is advanced in response to each Print Compare or Space signal applied to NOR 44 to advance, and through the Decode Circuits 3 2, 34 and 36 sequentially illuminate thelight-emitting diodes to indicate the next position to be printedfAt the same time the Inverter 76 causes the output of the NAND Gate 80 to be up since the output of Inverter 76 will be down. Capacitor C, therefore, charges throughidiode D1. The output of Inverter 66 will be down, pulling the base of transistor T1 to ground so that the transistor is reverse biased and therefore turned off. Transistor T2 is also in the off condition. I v

When the Switch 70 is thrown to the CE adjust position, the input of the Inverter 76 is grounded, so that the output is up, and clock pulses are gated by the NAND 54 and applied through NOR 48 to advance the Counter 30'. The input to NAND 80 is now up whenever the display control signal applied to Conductor 82 is'up, and the output of the NAND 80 is. down, so that the output of Inverter 66 is up. The Ramp Capacitor C will start to discharge through the resistor R. At some point on the slope of the discharge curve the emitter of transistor T1 will fall below the base potential, turning transistor T1 on. This turns transistor T2 on resulting in closing the gate to the Counter 30 at NAND 54, since the output of Inverter 68 is down. The last count ,of the Counter 30 will be frozen and displayed until Display Control signal goes down. Then the Counter 30 will be reset and capacitor C starts to charge again. This cycle repeats about three times a second. The calibration of the Ramp Circuit 60 should be such that at specified air gap and perfect tracking the displayed sition of the type belt may be adjusted by tilting the axis of the Pulley 18 until the count reaches the specified optimum registration value. The Switch may then be returned to the normal position, and the Counter 30 will continue to operate the light-emitting Diodes 41-42 to indicate the next position to be printed.

From the above description and the accompanying drawing it will be apparent that a D-C analog voltage proportional to the emitter signal is developed which provides an indication of the type belt vertical position. This signal is converted from an analog to a digital signal and the digital value of the converted signal is displayed on the indicator to provide an indication of the print belt position. Since the indicating lamps normally indicate the next position to be printed, the invention provides a dual function. In addition, the'circuit gives an indication of gap adjustment and/or transducer output.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and the scope of the invention.

What is claimed is: v

1. In a printer for printing at a plurality of print positions along a print line of a document,

apair of spaced apart pulleys mounted for rotation about respective axes,

an endless type belt comprising a flexible metal band positioned on said pulleys to move along said print line, said band having spaced type characters along said band in line with said print line for impacting with said document and a plurality of spaced apart timing marks extending transversely of said belt, the axis of one of said pulleys being tiltable to raise or lower said belt on said pulleys for thus correcting the lateral registration of said belt,

means including a transducer normally aligned with said timing marks for detecting said timing marks as they move past said transducer and producing an outputpulse for each timing mark, said outputs being also proportional to changes in the position of said belt and timing mark transversely of the lengthwise direction of said belt above and below said print line and a common indicating means comprising a counter,

first gate means connecting said counter to a printer control source for indicating which print position is next to print,

second gate means connecting said counter to a clock pulse source,

a timing circuit connected to said second gate means to control connection of said counter to said clock pulse source said timing circuit being responsive to the amplitude of the output of said transducer,

switch means normally positioned in a first position to activate said first gate means to connect said counter to said printer control source to indicate which print position is next to print, said switch means being positionable in a second position to render said first gate means ineffective and to render effective said second gate means to connect said common counter to said clock pulse source to indicate the transverse position of said type belt relative to said print line and indicate that the axis of one of said pulleys should be tilted to correct for lateral registration of said belt. a 

1. In a printer for printing at a plurality of print positions along a print line of a document, a pair of spaced apart pulleys mounted for rotation about respective axes, an endless type belt comprising a flexible metal band positioned on said pulleys to move along said print line, said band having spaced type characters along said band in line with said print line for impacting with said document and a plurality of spaced apart timing marks extending transversely of said belt, the axis of one of said pulleys being tiltable to raise or lower said belt on said pulleys for thus correcting the lateral registration of said belt, means including a transducer normally aligned with said timing marks for detecting said timing marks as they move past said transducer and producing an output pulse for each timing mark, said outputs being also proportional to changes in the position of said belt and timing mark transversely of the lengthwise direction of said belt above and below said print line and a common indicating means comprising a counter, first gate means connecting said counter to a printer control source for indicating which print position is next to print, second gate means connecting said counter to a clock pulse source, a timing circuit connected to said second gate means to control connection of said counter to said clock pulse source said timing circuit being responsive to the amplitude of the output of said transducer, switch means normally positioned in a first position to activate said first gate means to connect said counter to said printer control source to indicate which print position is next to print, said switch means being positionable in a second position to render said first gate means ineffective and to render effective said second gate means to connect said common counter to said clock pulse source to indicate the transverse position of said type belt relative to said print line and indicate that the axis of one of said pulleys should be tilted to correct for lateral registration of said belt. 